Chris Powell tweaked his squad for the trip to Reading, with Cedric Evina coming in for his first start of the season at the expense of Johnnie Jackson.
The skipper dropped to the bench, with Evina playing on the left of midfield.
Charlton looked to have won a penalty after 10 minutes when Stephen Kelly clipped Simon Church from behind. But to the dismay of the former Royals striker, referee Darren Sheldrake waved play on.
Three minutes later, the Addicks’ woes increased when Reading took the lead. Dale Stepens gave possession away in midfield, the ball was switched to Billy Sharp who rifled his shot past Ben Alnwick’s right hand to score the decisive goal.
It was 44 minutes before Charlton managed a shot and in the last minute of the half, they should have restored parity. Church was put clear with just Alex McCarthy to beat but shot tamely at the Reading keeper.
The second half saw Charlton in the ascendancy for long periods but despite creating numerous chances, the visitors failed to test McCarthy.
Twenty minutes from time Powell made a triple substitution with Marvin Sordell, Danny Green and Johnnie Jackson replacing Church, Stephens and Evina.
The changes added further impetus and Sordell did manage to glance Green’s shot into the net but he was clearly offside.
The Addicks huffed and puffed but could not find the decisive touch to draw level.
With results elsewhere going against them, Charlton’s game at resurgent Yeovil on Saturday takes on added importance.
Charlton: Alnwick; Wilson, Morrison, Dervite, Wiggins; Stewart, Cousins, Stephens (Jackson 70), Evina (Green 70); Kermorgant, Church (Sordell 70).
Subs (not used): Pope, Hughes, Pritchard, Wood.
Booked: Morrison 26 (foul).
Reading: McCarthy; Cummings, Gorkss, Pearce, Kelly; Guthrie, Williams (Akpan 64), McCleary (Blackman 93), McAnuff; Pogrebnyak, Sharp (Robson-Kanu 67).
Subs (not used): Federici, Obita, Drenthe, Blackman, Le Fondre.
Booked: Kelly 29 (foul), Gorkss 71 (foul).
Goal: Sharp 13.
Referee: Darren Sheldrake (Surrey).
Attn: 18,149 (836 Charlton).